Peripheral and central ambulatory blood pressure in relation to ECG voltage

Abstract

BackgroundThe heart ejects in the central elastic arteries. No previous study addressed the question whether ECG voltages are more closely associated with central than with peripheral blood pressure (BP).MethodsUsing the oscillometric Mobil-O-Graph 24 h PWA monitor, we measured brachial, central BP and central hemodynamics over 24 hours in 177 men (mean age, 29.1 years), and linked to ECG voltages.ResultsFrom wakefulness to sleep, as documented by diaries, systolic/diastolic BP decreased by 11.7/13.1 mmHg peripherally and by 9.3/13.6 mmHg centrally, whereas pulse pressure (PP) increased by 4.3 mmHg. Over 24 hours and the awake and asleep periods, the peripheral-minus-central differences in systolic/diastolic BPs and pulse pressure averaged 11.8/−1.6, 12.7/−1.8 and 10.3/−1.2 mmHg and 13.4, 14.4 and 11.5 mmHg, respectively (P < 0.0001). Cornel voltage and index averaged 1.18 mV and 114.8 mV × ms. The Cornell voltages were 0.104/0.086 and 0.082/0.105 mV higher in relation to brachial 24-h and asleep systolic/diastolic BP (per 1-SD), respectively, and 0.088/0.90 mV and 0.087/0.107 mV higher in relation to central BP. The corresponding estimates for the Cornel indexes were 9.6/8.6 and 8.2/105 mV × ms peripherally and 8.6/8.9 and 8.8/10.7 mV × ms centrally. The regression slopes were similar for brachial and central BP (P ≥ 0.054). Associations of the ECG measurements with awake BP, PP, the augmentation ratio and pressure amplification did not reach significance.ResultsNIAGEN® safely and effectively raised circulating levels of NAD+ and related metabolites. Although no effect was observed on endothelial function, NIAGEN® significantly lowered PWV as well as systolic (SBP) and diastolic blood pressure (DBP) in all subjects (P < 0.05). When separated by baseline BP status, the BP-lowering effect of NIAGEN® was observed in pre-hypertensive (pHTN, n = 13) but not normotensive (N = 11) individuals (P < 0.01). Interestingly, NIAGEN® was lowered in all subjects regardless of baseline BP status.ConclusionChronic NIAGEN® supplementation lowers SBP in pHTN older adults and reduces aortic stiffness, independent of baseline blood pressure status.TableAssociation of ECG Cornell voltage and indexes with peripheral and central BP.Cornell voltage (SV3 + RaVL, mV)Cornell index (Cornell voltage × QRS duration, mV · ms)Peripheral BPCentral BPPeripheral BPCentral BPEstimate (95% CI)PEstimate (95% CI)PEstimate (95% CI)PEstimate (95% CI)PSystolic BP24-h0.104 (0.016 to 0.191)0.0210.088 (0.0003 to 0.177)0.0499.61 (0.65 to 18.57)0.0368.58 (−0.40 to 17.56)0.061Awake0.086 (−0.001 to 0.175)0.0540.062 (−0.026 to 0.151)0.177.69 (−1.30 to 16.69)0.0935.80 (−3.23 to 14.82)0.21Asleep0.082 (−0.006 to 0.170)0.0680.087 (−0.001 to 0.175)0.0538.17 (−0.82 to 17.16)0.0758.76 (−0.217 to 17.74)0.056Diastolic BP24-h0.086 (−0.002 to 0.174)0.0560.090 (0.002 to 0.178)0.0458.57 (−0.41 to 17.55)0.0618.93 (−0.04 to 17.90)0.051Awake0.056 (−0.032 to 0.145)0.210.060 (−0.029 to 0.149)0.185.62 (−3.42 to 14.65)0.225.97 (−3.06 to 15.00)0.19Asleep BP0.105 (0.017 to 0.192)0.0200.107 (0.019 to 0.194)0.01710.53 (1.60 to 19.47)0.02110.71 (1.78 to 19.64)0.019Pulse pressure24-h0.040 (−0.049 to 0.129)0.380.016 (−0.073 to 0.105)0.723.07 (−5.99 to 12.13)0.501.31 (−7.76 to 10.38)0.77Awake0.048 (−0.041 to 0.137)0.290.012 (−0.077 to 0.101)0.783.63 (−5.43 to 12.68)0.430.68 (−8.40 to 9.74)0.88Asleep0.001 (−0.091 to 0.088)0.980.001 (−0.087 to 0.090)0.98−0.29 (−9.37 to 8.78)0.950.21 (−8.86 to 9.28)0.96ECG refers to electrocardiography. BP stands for blood pressure. Cornell voltage is the voltage sum of S wave in precordial V3 lead (SV3) and R wave in limb aVL lead (ReVL), while Cornell index is the product of QRS duration multiplied by the Cornell voltage. The estimate (95% Confidence Interval, CI) of the association was unadjusted and expressed as 1-SD increase of BP. P value is for significance of the estimate. The association estimates of Cornell voltage (P ≥ 0.054) and index (P ≥ 0.079) with central BP were not significantly different from those estimates with peripheral measurements.ConclusionsThe diurnal rhythm of peripheral and central BP run in parallel. Central BP does not improve the association of Cornell voltage or index with peripheral BP.